Xmr-sensor and method for manufacturing the xmr-sensor

ABSTRACT

An XMR-sensor and method for manufacturing the XMR-Sensor are provided. The XMR-sensor includes a substrate, a first contact, a second contact and an XMR-structure. The substrate includes a first main surface area and a second main surface area. The first contact is arranged at the first main surface area and the second contact is arranged at the second main surface area. The XMR-structure extends from the first contact to the second contact such that an XMR-plane of the XMR-structure is arranged along a first direction perpendicular to the first main surface area or the second main surface area.

REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. application Ser. No.13/741,693 filed on Jan. 15, 2013, the contents of which areincorporated by reference in their entirety.

FIELD

Embodiments relate to an XMR-sensor. Further embodiments relate to amethod for manufacturing an XMR-sensor. Further embodiments relate to abridge circuit comprising four XMR-sensors. Some embodiments relate toan integration concept for a vertical AMR sensor.

BACKGROUND

Magnetic field sensors are used for a variety of applications. Manyapplications require the measurement of all three components of amagnetic field, e.g., compass applications. For two dimensionalmeasurements the XMR-technology is very suitable due to the sensitivityto in-plane fields (e.g., along the x-axis and the y-axis), but fieldsperpendicular to the XMR-plane (e.g., along the z-axis) cannot bedetected without further measures.

SUMMARY

An XMR-sensor is provided. The XMR-sensor comprises a substrate, anXMR-structure, a first contact and a second contact. The XMR-structurecomprises at least one section which extends along a first directionperpendicular to the first main surface area or second main surface areasuch that an XMR-plane of the XMR-structure is arranged in the firstdirection. The first and second contacts are arranged to contact the atleast one section of the XMR-structure at different locations.

An XMR-sensor is provided. The XMR-sensor comprises a substrate, a firstcontact, a second contact and an XMR-structure. The substrate comprisesa first main surface area and a second main surface area. The firstcontact is arranged at the first main surface area and the secondcontact is arranged at the second main surface area. The XMR-structureextends from the first contact to the second contact such that anXMR-plane of the XMR-structure is arranged along a first directionperpendicular to the first main surface area or the second main surfacearea.

A method for manufacturing an XMR-sensor is provided. The methodcomprises providing a substrate having a first main surface area and asecond main surface area. The method comprises providing anXMR-structure comprising at least one section which extends along afirst direction perpendicular to the first main surface area or thesecond main surface area such that an XMR-plane of the XMR-structure isarranged in the first direction. The method comprises providing a firstand second contact arranged to contact the at least one section of theXMR-structure at different locations.

A bridge circuit comprising a first bridge section and a second bridgesection is provided. The first bridge section comprises a seriesconnection of a first XMR-sensor and a second XMR-sensor. The secondbridge section comprises a series connection of a third XMR-sensor and afourth XMR-sensor. Each of the first, second, third and fourthXMR-sensors comprises a substrate area, a first contact, a secondcontact and an XMR-structure. The substrate comprises a first mainsurface area and a second main surface area. The XMR-structure comprisesat least one section which extends along a first direction perpendicularto the first main surface area or the second main surface area, suchthat an XMR-plane of the XMR-structure is arranged in the firstdirection and in a second direction perpendicular to the firstdirection. The first and second contacts are arranged to contact the atleast one section of the XMR-structure at different locations.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure are described herein makingreference to the appended drawings.

FIG. 1A shows a cross-sectional view of an XMR-sensor according to anembodiment;

FIG. 1B shows a perspective view of the XMR-sensor according to anembodiment;

FIG. 1C shows a perspective view of the XMR-sensor according to afurther embodiment;

FIG. 2 shows a flow chart of a method for manufacturing the XMR-sensor;

FIG. 3A shows a cross-sectional view of the XMR-sensor duringmanufacturing after providing the substrate having the first mainsurface area and the second main surface area;

FIG. 3B shows a cross-sectional view of the XMR-sensor duringmanufacturing after etching the substrate;

FIG. 3C shows a cross-sectional view of the XMR-sensor duringmanufacturing after depositing a ferromagnetic layer on the second mainsurface area and the etched structure;

FIG. 3D shows a cross-sectional view of the XMR-sensor duringmanufacturing after depositing a dielectric layer on the ferromagneticlayer;

FIG. 3E shows a cross-sectional view of the XMR-sensor duringmanufacturing after chemical mechanical polishing the XMR-sensor andproviding the second contact;

FIG. 4A shows a three-dimensional view of the first contact, the secondcontact and the XMR-structure which extends from the first contact tothe second contact;

FIG. 4B shows a three-dimensional view of the XMR-sensor shown in FIG.4A further comprising a current conductor 105 arranged at or parallel tothe second main surface area.

FIG. 4C shows a three-dimensional view of the XMR-sensor shown in FIG.4A further comprising a current conductor 105 arranged at or parallel tothe first main surface area.

FIG. 5 shows an illustrative view of the current distribution within theXMR-structure shown in FIG. 4A;

FIG. 6 shows in a diagram the simulated output signal based on ay-component of an external magnetic field; and

FIG. 7A shows a block diagram of a bridge circuit comprising fourXMR-sensors.

FIG. 7B shows a block diagram of the bridge circuit shown in FIG. 7A,wherein each of the XMR-sensors comprises a current conductor.

FIG. 8A shows a cross-sectional view of the XMR-sensor duringmanufacturing after depositing the ferromagnetic layer on the secondmain surface area and the etched structure.

FIG. 8B shows a top view of the XMR-sensor during manufacturing afterdepositing the ferromagnetic layer on the second main surface area andthe etched structure.

FIG. 8C shows a top view of the XMR-sensor during manufacturing afteretching the ferromagnetic layer at the lower portion of the edgedstructure.

FIG. 8D shows a top view of the XMR-sensor during manufacturing afterapplying a lithographic mask.

FIG. 8E shows a top view of the XMR-sensor during manufacturing afteretching the XMR-layer.

Equal or equivalent elements or elements with equal or equivalentfunctionality are denoted in the following description by equal orequivalent reference numerals.

DETAILED DESCRIPTION

In the following description, a plurality of details are set forth toprovide a more thorough explanation of embodiments of the presentdisclosure. However, it will be apparent to those skilled in the artthat embodiments of the present disclosure may be practiced withoutthese specific details. In other instances, well-known structures anddevices are shown in block diagram form rather than in detail in orderto avoid obscuring embodiments of the present disclosure. In addition,features of the different embodiments described hereinafter may becombined with each other, unless specifically noted otherwise.

In the drawings, a Cartesian coordinate system comprising a first axis,a second axis and a third axis (substantially) perpendicular to eachother is shown for illustration purposes.

Moreover, subsequently, a first direction describes a direction parallelto or along the first axis of the Cartesian coordinate system, wherein asecond direction describes a direction parallel to or along the secondaxis of the Cartesian coordinate system, and wherein a third directiondescribes a direction parallel to or along the third axis of theCartesian coordinate system.

The first axis of the Cartesian coordinate system can be denoted as thez-axis, wherein the second axis of the Cartesian coordinate system canbe denoted as the y-axis, and wherein the third axis of the Cartesiancoordinate system can be denoted as the x-axis. Moreover, the firstdirection can be denoted as the z-direction, wherein the seconddirection can be denoted as the y-direction, and wherein the thirddirection can be denoted as the x-direction.

FIG. 1(a) shows a cross-sectional view of an XMR-sensor 100 according toan embodiment. The XMR-sensor 100 comprises a substrate 102, a firstcontact 104, a second contact 106 and an XMR-structure 108. Thesubstrate 102 comprises a first main surface area 110 and a second mainsurface area 112. The XMR-structure 108 comprises at least one sectionthat extends along the first direction perpendicular to the first mainsurface area 110 and/or the second main surface area 112 such that anXMR-plane of the XMR-structure 108 is arranged in the first direction.The first contact 104 and the second contact 106 can be arranged tocontact the at least one section of the XMR-structure 108 at differentlocations.

In embodiments, the XMR-structure 108 is arranged such that theXMR-plane, i.e., the active or sensitive area of the XMR-sensor 100, isarranged perpendicular to the first main surface area 110 and/or thesecond main surface area 112. Thus, the XMR-sensor 100 is sensitive tomagnetic fields or magnetic field components perpendicular to the firstmain surface area 110 and/or the second main surface area 112.

As shown in FIG. 1(a), the first contact 104 and the second contact 106can be arranged to contact the at least one section of the XMR-structureat different locations, e.g., a first location and a second locationdifferent from the first location, along the first direction.

For example, the first contact 104 can be arranged at the first mainsurface area 110, wherein the second contact 106 can be arranged at thesecond main surface area 112. The XMR-structure 108 can extend from thefirst contact 104 to the second contact 106 such that the XMR-plane ofthe XMR-structure 108 is arranged along the first directionperpendicular to the first main surface area 110 and/or the second mainsurface area 112.

In some embodiments, the first main surface area 110 can span a planealong the second direction (e.g., y-direction) and the third direction(e.g., x-direction), perpendicular to the first direction (e.g.,z-direction).

Similarly, the second main surface area 112 can span a plane parallel tothe second direction (e.g., y-direction) and the third direction (e.g.,x-direction), perpendicular to the first direction (e.g., z-direction).

In other words, the idea is to tune the sensitive plane of theXMR-sensor 100 parallel to the first axis (e.g., z-axis) in order toobtain, in a direct way, a sensitivity along the first axis (e.g.,z-axis).

Thereby, the XMR-structure 108 can be an AMR-structure (AMR=AnisotropicMagneto Resistive), a GMR-structure (GMR=Giant Magneto Resistive), aTMR-structure (TMR=Tunnel Magneto Resistive), or a CMR-structure(CMR=Colossal Magneto Resistive) or an EMR-structure (EMR=ExtraordinaryMagneto Resistive). Thus, XMR may refer to AMR, GMR, TMR, CMR or EMR.

Note that a possible integration concept is explained in someembodiments by means of an AMR-sensor, since its essential component isonly one permalloy layer, e.g., NiFe, of a certain thickness (e.g., 10to 50 nm, or 5 to 70 nm, or 20 to 40 nm). In other words, in someembodiments, a way how to implement an AMR-technology sensitive tomagnetic fields perpendicular to the substrate plane (or first mainsurface area 110 and/or second main surface area 112) is described.

As indicated in FIG. 1(a), the substrate 102 can comprise at least twosubstrate layers 102_1 to 102_n (n≧2) stacked in the first direction.The first contact 104 can be arranged in or at a first substrate layer102_1 of the at least two substrate layers 102_1 to 102_n (n≧2), andwherein the second contact 106 can be arranged in or at a secondsubstrate layer 102_2 of the at least two substrate layers 102_1 to102_n (n≧2).

Note that the substrate 102 can comprise up to n substrate layers 102_1to 102_n, wherein n is a natural number equal to or greater than 2(n≧2). For example, as shown in FIG. 1a , the substrate can comprise afirst substrate layer 102_1 and a second substrate layer 102_2.Naturally, the substrate can also comprise further substrate layers102_3 to 102_n, e.g., a third substrate layer 102_3 and a fourthsubstrate layer 102_4 arranged between the first substrate layer 102_1and the second substrate layer 102_2.

At least the first substrate layer 102_1 and the second substrate layer102_2 of the at least two substrate layers 102_1 to 102_n (n≧2) cancomprise a dielectric material. For example, the first substrate layer102_1 and the second substrate layer 102_2 can comprise oxide ornitride.

FIG. 1(b) shows a three-dimensional view of the XMR-sensor 100.

As indicated in FIG. 1b , the first contact 104 and the second contact106 can be arranged at different positions along the second direction(e.g., y-direction) perpendicular to the first direction (e.g.,z-direction).

The XMR-structure 108 may extend from the first contact 104 to thesecond contact 106 such that the XMR-plane of the XMR-structure isarranged along the first direction (e.g., z-direction) and the seconddirection (e.g., y-direction) perpendicular to the first direction(e.g., z-direction).

Further, the XMR-structure 108 may extend from the first contact 104 tothe second contact 106 such that a first edge 114 of the XMR-structure108 is arranged along the first direction (e.g., z-direction) and asecond edge 116 of the XMR-structure 108 is arranged along the seconddirection (e.g., y-direction) perpendicular to the first direction(e.g., z-direction).

Naturally, also a third edge 118 of the XMR-structure 108 can bearranged along the first direction (e.g., z-direction), wherein a fourthedge 120 of the XMR-structure 108 can be arranged along the seconddirection (e.g., y-direction).

The XMR-structure 108 with the four edges 114 to 120 can comprise a(substantially) rectangular or quadratic shape.

Thus, a current applied to the first contact 104 (or the second contact106) may flow through the XMR-structure 108 to the second contact 106(or first contact 104) at a certain angle with respect to the first mainsurface area 110 and/or the second main surface area 112. The certainangle can be in a range between 10° and 80°, between 20° and 70°,between 30° and 60°, or between 40° to 50°. A modification andoptimization of the mean certain angle can be done by an adjustment ofthe ratio of the XMR structure height 140 and the distance of the firstand second contact 142. Furthermore, also a vertical current directionparallel to the first direction of approximately 0° can be obtained.

As shown in FIG. 1(b), the first main surface area 110 and the secondmain surface area 112 can be parallel to each other and face each other.

Moreover, a dimension of the substrate 102 along the first direction(e.g., z-direction) can be smaller than a dimension of the substrate 102along the second direction (e.g., y-direction) and/or a dimension of thesubstrate 102 along the third direction (e.g., x-direction),perpendicular to the first direction (e.g., z-direction).

FIG. 1(c) shows a three-dimensional view of the XMR-sensor 100 accordingto a further embodiment. In contrast to FIG. 1(b), in which the firstcontact 104 is arranged to contact the at least one section of theXMR-structure 108 directly, in FIG. 1(c) the first contact 104 isarranged to contact the at least one section of the XMR-structure 108 bymeans of a low impedance connection 109.

The low impedance connection 109 can be a connection having an impedancesmaller than 10Ω, 1Ω, 0.1Ω, 0.01Ω, or 0.001Ω, such as a wire, a trace,or a combination of a via and a trace, for example.

Naturally, also the second contact 106 can be arranged to contact the atleast one section of the XMR-structure 108 by means of a low impedanceconnection.

Note that the first contact 104 may contact the at least one section ofthe XMR-substrate 108 directly or by means of a low impedance connectionat a first location, wherein the second contact 106 may contact the atleast one section of the XMR-substrate 108 directly or by means of a lowimpedance connection at a second location different from the firstlocation (along the first direction). As indicated in FIGS. 1(a) to1(c), a distance between the first location and the second locationalong the first direction can be equal to a dimension of theXMR-structure 108 along the first direction. Naturally, the distancebetween the first location and the second location can also be smallerthan the dimension of the XMR-structure 108 along the first direction.

Referring to FIG. 1(c), the first contact 104 can be arranged at thefirst main surface area 110, which is indicated with reference numeral104 a, and be connected to the at least one section of the XMR-structure108 by means of the low impedance connection 109, which is indicatedwith reference numeral 109 a.

Moreover, the first contact 104 can be arranged at the second mainsurface area 112, which is indicated with reference numeral 104 b, andbe connected to the at least one section of the XMR-structure 108 bymeans of the low impedance connection 109, which is indicated withreference numeral 109 b.

In the following, a method for manufacturing the XMR-sensor 100 shown inFIG. 1(a) and/or FIG. 1(b) is described.

FIG. 2 shows a flow chart of a method 200 for manufacturing theXMR-sensor 100. The method 200 comprises providing a substrate 102having a first main surface area 110 and a second main surface area 112at 202. The method 200 comprises providing an XMR-structure 108 thatextends from the first contact 104 to the second contact 106 such thatan XMR-plane of the XMR-structure 108 is arranged along a firstdirection perpendicular to the first main surface area 110 and/or thesecond main surface area 112 at 208. The method comprises providing afirst contact 104 and a second contact 106 arranged to contact the atleast one section of the XMR-structure 108 at different locations at204.

Subsequently, the method 200 for manufacturing the XMR-sensor isdescribed by way of example making reference to FIGS. 3(a) to 3(e)showing cross-sectional views of the XMR-sensor 100 duringmanufacturing.

Thereby, it is assumed that the first contact 104 is arranged at thefirst main surface area 110, wherein the second contact 106 is arrangedat the second main surface area 112, and wherein the XMR-structureextends from the first contact 104 to the second contact 106 such thatthe XMR-plane of the XMR-structure 108 is arranged along the firstdirection perpendicular to the first main surface area 110 and/or thesecond main surface area 112.

FIG. 3(a) shows a cross-sectional view of the XMR-sensor 100 duringmanufacturing after providing 202 the substrate 102 having the firstmain surface area 110 and the second main surface area 112.

As indicated in FIG. 3(a), providing 202 the substrate 102 can compriseproviding a first substrate layer 102_1 (dielectric 1, e.g., oxide) andproviding a second substrate layer 102_2 (dielectric 2, e.g., oxide).

Providing the first contact 104 at 204 can comprise providing the firstcontact 104 such that the first contact is arranged in or at the firstsubstrate layer 102_1.

FIG. 3(b) shows a cross-sectional view of the XMR-sensor 100 duringmanufacturing after etching the substrate 102.

Providing the XMR-structure 108 at 208 can comprise etching thesubstrate 102 from the second main surface area 112 against or oppositeto the first direction at least until reaching the first contact 104 inorder to obtain an etched structure 126 in which the first contact 104is at least partly exposed.

The etched structure 126 can be arranged such that a first wall 128 ofthe etched structure 126 extends from the second main surface area 112to the first contact 104.

In other words, FIG. 3(b) shows a cross-sectional view of the XMR-sensor100 after a lithographic and dielectric 2 etch step.

FIG. 3(c) shows a cross-sectional view of the XMR-sensor 100 duringmanufacturing after depositing a ferromagnetic layer 108 on the secondmain surface area 112 and the etched structure 126.

Providing the XMR-structure 108 at 208 can comprise depositing aferromagnetic layer (or XMR-layer) 108 on the second main surface area112 and the etched structure 126 such that the ferromagnetic layer 108rests on the etched structure 126 and such that at least a part of theferromagnetic layer 108 extends from the second main surface area 112 tothe first contact 104 along the edge 128.

FIG. 3(d) shows a cross-sectional view of the XMR-sensor 100 duringmanufacturing after depositing a dielectric layer 129 on theferromagnetic layer 108.

Providing 208 the XMR-structure 108 can further comprise depositing thedielectric layer 129 on the ferromagnetic layer 108.

FIG. 3(e) shows a cross-sectional view of the XMR-sensor 100 duringmanufacturing after chemical mechanical polishing the XMR-sensor 100 andproviding the second contact 106.

In other words, FIG. 3(e) shows a CMP process (CMP=Chemical MechanicalPolishing) and metal deposition/etch.

Providing the XMR-structure 108 at 208 can comprise chemical mechanicalpolishing the XMR-sensor 100 beginning from a surface 130 of thedielectric layer 129 until at least the second main surface area 112 ofthe substrate 102 and the part of the ferromagnetic layer 108 thatextends from the second main surface area 112 to the first contact 104is exposed.

The second contact 106 can be provided at the second main surface area112 such that the part of the ferromagnetic layer 108 that extends fromthe second main surface area 112 to the first contact 104 forms theXMR-structure 108.

As shown in FIGS. 3(a) to 3(e), the method 200 allows the fabrication ofgrooves 126 having sidewalls 128 deposited with permalloy 108 of adefined thickness.

In other words, FIGS. 3(a) to 3(e) show a schematic of a possibleprocess. After providing a second dielectric layer 102_2 on a wiringmetal 104 with a thickness which will be approximately the height of thevertical AMR-layer (FIG. 3(a)), a groove 126 can be etched into thesecond dielectric layer 102_2 (FIG. 3(b)). Then, a deposition processwith good edge coverage can be applied where the side and bottom wallsof the groove 126 are covered with a highly permeable film which shows asignificant AMR effect, e.g., permalloy Ni81Fe19 (FIG. 3(c)). Next, adielectric film 129 (e.g., oxide) can be deposited (FIG. 3(d)) andpolished together with the ferromagnetic material 108 outside the groove126 (FIG. 3(e)). As a result, a flat surface 112 is obtained and the topside of the vertical AMR-layer 108 can be contacted, e.g., by a furthermetal 106.

According to a further embodiment, the manufacturing steps shown inFIGS. 3(d) and 3(e) can be exchanged by the manufacturing steps shown inFIGS. 8(c) to 8(e) as will become clear from the following description.

FIG. 8(a) shows a cross-sectional view of the XMR-sensor 100 duringmanufacturing after depositing the ferromagnetic layer 108 on the secondmain surface area 112 and the etched structure 126 as already shown inFIG. 3(c).

FIG. 8(b) shows a top view of the XMR-sensor 100 during manufacturingafter depositing the ferromagnetic layer 108 on the second main surfacearea 112 and the etched structure 126.

FIG. 8(c) shows a top view of the XMR-sensor 100 during manufacturingafter etching the ferromagnetic layer 108 at the lower portion of theedged structure 126.

Providing the XMR-structure 108 can comprise etching the XMR-layer 108at the bottom of the etched structure 126 while maintaining the part ofthe XMR-layer 108 which extends from the second main surface area 112 tothe first contact 104.

In other words, the step of providing the XMR-structure 108 can compriseremoving the XMR-material 108 from the bottom plane of the etchedstructure 126 by an etch process.

For example, the XMR-material 108 can be removed from the bottom of theetched structure 126 with an (anisotropic) etch process.

FIG. 8(d) shows a top view of the XMR-sensor 100 during manufacturingafter applying a lithographic mask 190.

Providing the XMR-structure 108 can comprise applying a lithographicmask 190 on a portion of the etched structure 126 such that thelithographic mask 190 rests on a portion of the XMR-layer 108, theportion of the XMR-layer 108 including the part of the XMR-layer 108which extends from the second main surface area 112 to the first contact104.

In other words, a lithography step can be applied where only a portionof the etched structure 126 is covered by a resist 190.

FIG. 8(e) shows a top view of the XMR-sensor 100 during manufacturingafter etching the XMR-layer 108.

Providing the XMR-structure 108 can comprise etching a portion theXMR-layer 108 while maintaining the portion of the XMR-layer 108 onwhich the lithographic mask 190 rests.

In other words, providing the XMR-structure 108 can comprise alithography step and a subsequent etch process step where all XMRmaterial is removed such that the XMR material remains only in selectedregions of the side walls of the etched structure

For example, after an (isotropic) etch process only XMR material 108beneath the resist remains at the side walls 128. As a result, the XMRsensor structure 108 exhibits two additional edges 114 and 118 (see FIG.1(b)). The benefit is no electric and magnetic interference from otherregions. Moreover, more than one XMR sensor structure 108 can bemanufactured within one etched groove 126.

Alternatively, the removal of the XMR material from the bottom of theetched structure 126 can also be omitted.

In the following, the functionality of the XMR-sensor 100 is describedby way of example making reference to FIGS. 4a to 6.

FIG. 4(a) shows a three-dimensional view of the first contact 104, thesecond contact 106 and the XMR-structure 108 which extends from thefirst contact 104 to the second contact 106.

The first contact 104 and the second contact 106 are arranged atdifferent positions along the second direction (e.g., y-direction)perpendicular to the first direction (e.g., z-direction).

As shown in FIG. 4(a), a height 140 (h) of the XMR-structure 108 can bedefined along the first direction (e.g., z-direction), wherein adistance 142 (d) between the first contact 104 and the second contact106 can be defined along the second direction (e.g., y-direction).

As already mentioned, by arranging the first contact 104 and the secondcontact 106 at different positions along the second direction (e.g.,y-direction), a current applied to the second contact 106 (or firstcontact 104) flows through the XMR-structure 108 to the first contact104 (or second contact 106) at a certain angle with respect to the firstmain surface area 110 and/or the second main surface area 112. Thiscurrent direction is indicated in FIG. 4(a) with the arrow 144 (netcurrent direction).

Due to the shape of the XMR-structure, i.e., that the dimension of theXMR-structure 108 along the first direction (e.g., z-direction) issmaller than a dimension of the XMR-structure along the second direction(e.g., y-direction), the anisotropic axis 146 (easy axis) of theXMR-structure 108 is parallel to the first direction (e.g.,y-direction).

In other words, FIG. 4(a) shows a schematic view of one side wall 128 ofthe groove 126 shown in FIG. 3 showing the top and bottom contact 104and 106 to realize a net current direction 144 having an angle to theeasy axis 146.

AMR-magnetic field strength sensors exhibit a predefined angle betweenthe easy axis of the magnetization and the current direction of ˜45° inorder to shift the working point into a region of the magnetoresistanceresponse with a linear and non-zero sensitivity (“barber poles” ofAMR-sensors). For a detection of the z-axis magnetic field component,the easy axis 146 can be in the x-/y-plane, e.g., along the y-axis asshown in FIG. 4(a). To obtain a certain angle between the easy axis 146and the net current direction 144, a top and bottom (punctual) contact104 and 106 can be spaced apart by a distance 142 (d) which can be inthe range of the wall height 140 (h).

FIG. 4(b) shows a three-dimensional view of the XMR-sensor 100 shown inFIG. 4(a) further comprising a current conductor 105. The currentconductor 105 can be arranged at or parallel to the second main surfacearea 112 such that a current 111 flowing through the current conductoris perpendicular to the XMR-plane of the XMR-structure 108. The current111 flowing through the current conductor 105 may generate a magneticfield parallel to the XMR-plane of the XMR-structure, e.g., parallel tothe second direction (e.g., y-direction).

FIG. 4(c) shows a three-dimensional view of the XMR-sensor 100 shown inFIG. 4(a) further comprising a current conductor 105. In contrast toFIG. 4(b), the current conductor 105 is arranged at or parallel to thefirst main surface area 110 but also such that a current 111 flowingthrough the current conductor is perpendicular to the XMR-plane of theXMR-structure 108.

In other words, a current conductor 105 providing a current flow 111parallel to the first main surface 110 or second main surface 112 andperpendicular to the plane of the XMR structure 108 can be provided asshown in FIG. 4(b). As a result, a magnetic field 107 is generatedparallel to the second direction (and parallel to the anisotropy axis146). The generated magnetic field 107 can be used to provide an initialmagnetic field to obtain defined magnetic conditions within the XMRsensor 100 to enhance the measurement accuracy. Further, especially incase of an AMR sensor structure the additional magnetic field can leadto so called flipping of the sensor layer magnetization from one side ofthe anisotropy axis 146 to the other side and vice versa, depending onthe applied current direction through the current conductor 105. FromAMR magnetic field strength sensors based on a Wheatstone full bridgeconcept it is well known that flipping of the sensor layer magnetizationalong the anisotropy axis 146 allows an exact measurement of the bridgeoffset and therefore, an accurate offset compensation. This isadvantageous to achieve a high measurement accuracy. The currentconductor can be implemented above the XMR structure 108 with aninsulating material in between as shown in FIG. 4(b). Alternatively, thecurrent conductor 105 can already be implemented within the firstsubstrate layer 102_1 as indicated in FIG. 4(c). In this case, thecurrent conductor 105 will be beneath the XMR structure 108. Also acombination of a current conductor 105 above and below the XMR structure108 for an enhancement of the achievable magnetic field is possible.

FIG. 5 shows an illustrative view of the current distribution within theXMR-structure 108 shown in FIG. 4(a).

As shown in FIG. 5, a current applied to the second contact 106 flowsthrough the XMR-structure to the first contact 104.

In other words, FIG. 5 shows the simulated current directiondistribution for the example in FIG. 4(a) with a wall height 140 of 2μm, a length 150 of 5 μm and a top contact 106/bottom contact 104displacement 142 of 2 μm.

A distinct angle variation of the current direction can be observed inthe region with significant current density between approximately 25°and 65°. By combining the calculated current distribution with thesimulated micro magnetic behavior, the simulated output signal upon anexternal y-component magnetic field can be obtained.

FIG. 6 shows in a diagram the simulated output signal based on theexternal y-component magnetic field.

Thereby, the ordinate describes the output signal (AMR-signal) inrelative units, wherein the abscissa describes the magnetic field inoersted.

In other words, FIG. 6 shows the resulting AMR-signal taking intoaccount the micro magnetic and electric behavior of a 5 μm long and 2 μmhigh permalloy side wall.

As shown in FIG. 6, the originally bell-shaped AMR-characteristic istransferred to a linear behavior which can be used to measure the fieldstrength. A mirroring of the positions of the top and bottom contact 104and 106 leads to a rotation of the net current direction by ˜90°. As aconsequence, the output characteristic of FIG. 6 is also mirrored. Thisis a prerequisite to realize a differential Wheatstone bridgeconfiguration.

As described above, some embodiments provide a vertical AMR-active layer108 having a magnetic field sensitivity perpendicular to the chip plane(z-axis) 110 or 112. The AMR-active layer 108 exhibits an easy axis 146perpendicular the z-axis and a defined angle (direction distribution)between the sensor current and the easy axis 146.

Thereby, the XMR-sensor 100 provides the advantage of no hysteresiseffects due to flux concentrator materials as they are widely used forother state-of-the-art technologies to realize a transformation ofperpendicular-to-plane field components into in-plane components. Theresult is a higher accuracy.

Furthermore, also other possibilities to realize a vertical orientatedAMR-layer are possible, like a plating processes of a groove having awidth of the final AMR-layer.

In addition to the z-component sensitive sensor structure, also usualXMR-sensor structures can be used to set the x- and/or y-component inorder to realize a fully three-dimensional sensor.

As already mentioned, by sweeping the position of the top and bottomcontact 104 and 106 position, two types of vertical AMR-elements can bedefined showing an inverted magnetoresistive characteristic. An adequatecombination allows the realization of a differential Wheatstone bridgeconfiguration as will become clear from the following description.

FIG. 7(a) shows a block diagram of a bridge circuit 180. The bridgecircuit 180 comprises a first bridge section 182 having a seriesconnection of a first XMR-sensor 100_1 and a second XMR-sensor 100_2.Furthermore, the bridge circuit 180 comprises a second bridge section184 having a series connection of a third XMR-sensor 100_3 and a fourthXMR-sensor 100_4.

The first XMR-sensor 100_1 comprises a substrate area, a first contact104_1, a second contact 106_1 and an XMR-structure 108_1. The substratearea comprises a first main surface area and a second main surface area.The first contact 104_1 is arranged at the first main surface area. Thesecond contact 106_1 is arranged at the second main surface area. TheXMR-structure 108_1 extends from the first contact 104_1 to the secondcontact 106_1 such that an XMR-plane of the XMR-structure 108_1 isarranged along a first direction perpendicular to the first main surfacearea and the second main surface area, and along a second directionperpendicular to the first direction.

The second XMR-sensor 100_2 comprises a substrate area, a first contact104_2, a second contact 106_2 and an XMR-structure 108_2. The substratearea comprises a first main surface area and a second main surface area.The first contact 104_2 is arranged at the first main surface area. Thesecond contact 106_2 is arranged at the second main surface area. TheXMR-structure 108_2 extends from the first contact 104_2 to the secondcontact 106_2 such that an XMR-plane of the XMR-structure 108_2 isarranged along a first direction perpendicular to the first main surfacearea and the second main surface area, and along a second directionperpendicular to the first direction.

The third XMR-sensor 100_3 comprises a substrate area, a first contact104_3, a second contact 106_3 and an XMR-structure 108_3. The substratearea comprises a first main surface area and a second main surface area.The first contact 104_3 is arranged at the first main surface area. Thesecond contact 106_3 is arranged at the second main surface area. TheXMR-structure 108_3 extends from the first contact 104_3 to the secondcontact 106_3 such that an XMR-plane of the XMR-structure 108_3 isarranged along a first direction perpendicular to the first main surfacearea and the second main surface area, and along a second directionperpendicular to the first direction.

The fourth XMR-sensor 100_4 comprises a substrate area, a first contact104_4, a second contact 106_4 and an XMR-structure 108_4. The substratearea comprises a first main surface area and a second main surface area.The first contact 104_4 is arranged at the first main surface area. Thesecond contact 106_4 is arranged at the second main surface area. TheXMR-structure 108_4 extends from the first contact 104_4 to the secondcontact 106_4 such that an XMR-plane of the XMR-structure 108_4 isarranged along a first direction perpendicular to the first main surfacearea and the second main surface area, and along a second directionperpendicular to the first direction.

Note that the first directions along which the XMR-planes of the first,second, third and fourth XMR-sensors 100_1 to 100_4 extend may beparallel to each other such that the first, second, third and fourthXMR-sensors 100_1 to 100_4 are sensitive to magnetic field componentsalong the first direction.

Moreover, the second directions along which the XMR-planes of the first,second, third and fourth XMR-sensors 100_1 to 100_4 extend may be, butdo not have to be, parallel to each other.

For example, if it is assumed that the bridge circuit 180 is arrangedrelative to a Cartesian coordinate system having an x′-axis, a y′-axis,and a z′-axis perpendicular to each other, then the XMR-planes of theXMR-sensors 100_1 to 100_4 can be arranged such that the firstdirections along which the XMR-planes of the XMR-sensors 100_1 to 100_4extend are parallel to the z′-axis, e.g., to achieve a sensitivity tomagnetic field components along the z′-axis.

A sensitivity of the XMR-planes of the XMR-sensors 100_1 to 100_4 tomagnetic field components along the x′-/y′-axis then depend on theorientations of the XMR-planes (or vertical planes) of the XMR-sensors100_1 to 100_4 to the stationary x′-/y′-axis. Naturally, it is possibleto build up the resistances (XMR-sensors) of the Wheatstone bridge suchthat the second directions along which the XMR-planes of the XMR-sensors100_1 to 100_4 extend are parallel to each other (e.g., parallel to thex′-axis or y′-axis), or in other words, such that the XMR-planes of theXMR-sensors 100_1 to 100_4 are parallel to each other. However, it wouldalso be possible to assemble any resistance of the Wheatstone bridge bymeans of a combination of mutually perpendicular XMR-planes (sensorplanes), for example, to reduce a dependence on the direction of thefields in the x′-/y′-plane, e.g., to achieve a reduced difference in thesensor signal when a parasitic field along the x′- or y′-axis ispresent.

In some embodiments, the first, second, third and fourth XMR-sensors100_1 to 100_4 can share the same substrate 102, i.e., the substrateareas of the first, second, third and fourth XMR-sensors 100_1 to 100_4can be substrate areas of the same substrate 102. In that case, thefirst main surface areas of the XMR-sensors 100_1 to 100_4 can be areasof a first main surface 110 of the substrate 102, wherein the secondmain surface areas of the XMR-sensors 100_1 to 100_4 can be areas of asecond main surface 112 of the substrate 102.

Naturally, it is also possible that each XMR-sensor of the XMR-sensors104_1 to 104_4 comprises its own substrate or that at least twoXMR-sensors of the XMR-sensors 104_1 to 104 share the same substrate,e.g., that the first and second XMR-sensors 100_1 and 100_2 share asubstrate and that the third and fourth XMR-sensor 100_3 and 100_4 sharea substrate.

Moreover, the first contacts 104_1 to 104_4 of the XMR-sensors 100_1 to100_4 can be arranged at a first plane perpendicular to the firstdirection (e.g., the first main surface 110 of the substrate 102),wherein the second contacts 106_1 to 106_4 of the XMR-sensors 100_1 to100_4 can be arranged at a second plane parallel to the first plane andperpendicular to the first direction (e.g., the second main surface 112of the substrate 102).

The first XMR-sensor 100_1 and the second XMR-sensor 100_2 can bearranged such that a distance along the second direction between thefirst contact 104_1 of the first XMR-sensor 100_1 and the first contact104_2 of the second XMR-sensor 100_2 is smaller (or greater in analternative embodiment) than a distance along the second directionbetween the second contact 106_1 of the first XMR-sensor 100_1 and thesecond contact 106_2 of the second XMR-sensor 100_2. Moreover, the thirdXMR-sensor 100_3 and the fourth XMR-sensor 100_4 can be arranged suchthat a distance along the second direction between the first contact104_3 of the third XMR-sensor 100_3 and the first contact 104_4 of thefourth XMR-sensor 100_4 is smaller (or greater in the alternativeembodiment) than a distance along the second direction between thesecond contact 106_3 of the third XMR-sensor 100_3 and the secondcontact 106_4 of the fourth XMR-sensor 100_4.

The first XMR-sensor 100_1 and the second XMR-sensor 100_2 can beconnected in series such that the first contact 104_1 of the firstXMR-sensor 100_1 and the first contact 104_2 of the second XMR-sensor100_2 are connected to each other. The third XMR-sensor 100_3 and thefourth XMR-sensor 100_4 can be connected in series such that the firstcontact 104_3 of the third XMR-sensor 100_3 and the first contact 104_4of the fourth XMR-sensor 100_4 are connected to each other.

FIG. 7(b) shows a block diagram of the bridge circuit 180 shown in FIG.7(a), wherein each of the XMR-sensors 100_1 to 100_4 comprises a currentconductor 105.

As described in detail with respect to FIGS. 4(b) and 4(c), the currentconductor 105 can be arranged at or parallel to the first main surfacearea 110 or second main surface area 112 of the respective XMR-sensor100_1 to 100_4 such that a current 111 flowing through the currentconductor is perpendicular to the XMR-plane of the respectiveXMR-structure 108_1 to 108_4.

As already mentioned, in some embodiments, the first, second, third andfourth XMR-sensors 100_1 to 100_4 can share the same substrate 102,wherein the first main surface areas of the XMR-sensors 100_1 to 100_4can be areas of a first main surface 110 of the substrate 102, whereinthe second main surface areas of the XMR-sensors 100_1 to 100_4 can beareas of a second main surface 112 of the substrate 102. In that case,the current conductor 105 can be arranged at or parallel to the firstmain surface 110 or second main surface of the substrate 102.

Although some aspects have been described in the context of anapparatus, it is clear that these aspects also represent a descriptionof the corresponding method, where a block or device corresponds to amethod step or a feature of a method step. Analogously, aspectsdescribed in the context of a method step also represent a descriptionof a corresponding block or item or feature of a correspondingapparatus. Some or all of the method steps may be executed by (or using)a hardware apparatus, like for example, a microprocessor, a programmablecomputer or an electronic circuit. In some embodiments, some one or moreof the most important method steps may be executed by such an apparatus.

The above described embodiments are merely illustrative for theprinciples of the present disclosure. It is understood thatmodifications and variations of the arrangements and the detailsdescribed herein will be apparent to others skilled in the art. It isthe intent, therefore, to be limited only by the scope of the impendingpatent claims and not by the specific details presented by way ofdescription and explanation of the embodiments herein.

1. An XMR-sensor, comprising: a substrate having a first main surfacearea and a second, different main surface area; an XMR-structurecomprising at least one section that extends along a first directionperpendicular to the first main surface area or the second main surfacearea such that an XMR-plane of the XMR-structure is arranged in thefirst direction; a first contact and a second contact arranged tocontact the at least one section of the XMR-structure at differentlocations of the XMR-structure; and a current conductor configured toconduct a current therethrough, and generate a magnetic field parallelto the XMR-plane of the XMR-structure in response to the conductingcurrent.
 2. The XMR-sensor according to claim 1, wherein the firstcontact and the second contact are arranged to contact the at least onesection of the XMR-structure at different locations along the firstdirection.
 3. The XMR-sensor according to claim 1, wherein the firstcontact and the second contact are arranged to contact the at least onesection of the XMR-structure directly or by means of a low impedanceconnection.
 4. The XMR-sensor according to claim 1, wherein thesubstrate comprises at least two substrate layers stacked with respectto one another in the first direction, wherein the first contact isarranged in or at a first substrate layer of the at least two substratelayers, and wherein the second contact is arranged in or at a secondsubstrate layer of the at least two substrate layers.
 5. The XMR-sensoraccording to claim 1, wherein at least the first substrate layer and thesecond substrate layer of the at least two substrate layers comprise adielectric material.
 6. The XMR-sensor according to claim 1, wherein thefirst contact and the second contact are arranged at different positionsof the XMR-structure along a second direction perpendicular to the firstdirection.
 7. The XMR-sensor according to claim 1, wherein a dimensionof the substrate along the first direction is smaller than a dimensionof the substrate along a second direction perpendicular to the firstdirection.
 8. The XMR-sensor according to claim 1, wherein the firstmain surface area and the second main surface area of the substrate areparallel to each other and face each other.
 9. The XMR-sensor accordingto claim 1, wherein the XMR-structure extends from the first contact tothe second contact such that the XMR-plane of the XMR-structure isarranged along the first direction and a second direction perpendicularto the first direction.
 10. The XMR-sensor according to claim 1, whereinthe XMR-structure extends from the first contact to the second contactsuch that a first edge of the XMR-structure is arranged along the firstdirection and a second edge of the XMR-structure is arranged along asecond direction perpendicular to the first direction.
 11. TheXMR-sensor according to claim 1, wherein the XMR-structure is anAMR-structure, a GMR-structure, a TMR-structure, a CMR-structure or anEMR-structure.
 12. The XMR-sensor according to claim 1, wherein thecurrent conductor is arranged at or parallel to the second main surfacearea or the first main surface area.
 13. A bridge circuit comprising afirst bridge section having a series connection of a first XMR-sensorand a second XMR-sensor, and a second bridge section having a seriesconnection of a third XMR-sensor and fourth XMR-sensor, wherein each ofthe first, second, third and fourth XMR-sensors comprises: a substratearea having a first main surface area and a second, different mainsurface area; an XMR-structure comprising at least one section thatextends along a first direction perpendicular to the first main surfacearea and the second main surface area, such that an XMR-plane of theXMR-structure is arranged in the first direction and in a seconddirection perpendicular to the first direction; a first contact and asecond contact arranged to contact the at least one section of theXMR-structure at different locations of the XMR-structure; and a currentconductor configured to conduct a current therethrough, and generate amagnetic field parallel to the XMR-plane of the XMR-structure inresponse to the conducting current.
 14. The bridge circuit according toclaim 13, wherein the XMR-planes of the XMR-structures of the first,second, third and fourth XMR-sensors are parallel to each other.
 15. Thebridge circuit according to claim 13, wherein the first contact and thesecond contact of each of the first, second, third and fourthXMR-sensors are arranged at different positions along the seconddirection of the XMR-structure; wherein the first XMR-sensor and thesecond XMR-sensor are arranged such that a distance along the seconddirection between the first contact of the first XMR-sensor and thefirst contact of the second XMR-sensor is smaller than a distance alongthe second direction between the second contact of the first XMR-sensorand the second contact of the second XMR-sensor; and wherein the thirdXMR-sensor and the fourth XMR-sensor are arranged such that a distancealong the second direction between the first contact of the thirdXMR-sensor and the first contact of the fourth XMR-sensor is smaller orgreater than a distance along the second direction between the secondcontact of the third XMR-sensor and the second contact of the fourthXMR-sensor.
 16. The bridge circuit according to claim 15, wherein thefirst XMR-sensor and the second XMR-sensor are connected in series suchthat the first contact of the first XMR-sensor and the first contact ofthe second XMR-sensor are connected to each other; and wherein the thirdXMR-sensor and the fourth XMR-sensor are connected in series such thatthe first contact of the third XMR-sensor and the first contact of thefourth XMR-sensor are connected to each other.
 17. The bridge circuitaccording to claim 13, wherein the substrate areas of the first, second,third and fourth XMR-sensors are arranged on a common substrate.
 18. Amethod for manufacturing an XMR-sensor, the method comprising: providinga substrate having a first main surface area and a second, differentmain surface area; providing an XMR-structure comprising at least onesection that extends along a first direction perpendicular to the firstmain surface area or the second main surface area such that an XMR-planeof the XMR-structure is arranged in the first direction; providing afirst contact and a second contact arranged to contact the at least onesection of the XMR-structure at different locations of theXMR-structure; wherein providing the substrate comprises providing afirst substrate layer and providing a second substrate layer; whereinthe first contact is arranged in the first substrate layer; whereinproviding the XMR-structure comprises etching the substrate from thesecond main surface area against the first direction at least untilreaching the first contact in order to obtain an etched structure inwhich the first contact is at least partly exposed; wherein the etchedstructure comprises side walls and a bottom wall; wherein the etchedstructure is arranged such that one of the sidewalls of the etchedstructure extends from the second main surface area to the firstcontact; wherein providing the XMR-structure comprises depositing anXMR-film on the second main surface area and on the etched structuresuch that the XMR-film rests on the etched structure covering the sidewalls and the bottom wall of the etched structure such that one part ofthe XMR-film, which rests on the one side wall of the etched structurethat extends from the second main surface area to the first contact,extends from the second main surface area to the first contact; andwherein the XMR-film is thinner than the second substrate layer.
 19. Themethod according to claim 18, wherein providing the XMR-structurecomprises: applying a lithographic mask on a portion of the etchedstructure such that the lithographic mask rests on a portion of theXMR-film, the portion of the XMR-film including the part of the XMR-filmalong the first wall that extends from the second main surface area tothe first contact; and etching the XMR-film while maintaining theportion of the XMR-layer on which the lithographic mask rests.
 20. Themethod according to claim 18, wherein providing the XMR-structurecomprises depositing a dielectric layer on the XMR-film.
 21. The methodaccording to claim 20, wherein providing the XMR-structure compriseschemical mechanical polishing beginning from a surface of the dielectriclayer until at least the second main surface area of the substrate andthe part of the XMR-film that extends from the second main surface areato the first contact is exposed, wherein the XMR-film comprises aferromagnetic material.
 22. The method according to claim 21, whereinthe second contact is provided at the second main surface area andcontacts the exposed ferromagnetic layer such that the part of theXMR-film that extends from the second main surface area to the firstcontact forms the XMR-structure.
 23. The method according to claim 18,wherein the step of providing the XMR structure comprises etching theXMR-layer at the bottom of the etched structure while maintaining thepart of the XMR-layer which extends from the second main surface area tothe first contact.